Enable default certificates handler

Previously the default ``certificates.available`` handler was
enabled without the charm authors intervention, this was changed
in I12f45236632b608e07fdd35d31b90b84ca92eb1f.

Change-Id: I85e82273f9a423ce0fe9d8462c82de608e3922f7

src/reactive/barbican_handlers.py

@@ -31,10 +31,10 @@ charm.use_defaults(
     'amqp.connected',
     'shared-db.connected',
     'identity-service.connected',
-    'identity-service.available',  # enables SSL support
     'config.changed',
     'update-status',
     'upgrade-charm',
+    'certificates.available',
 )
 
 

unit_tests/test_barbican_handlers.py

@@ -30,9 +30,9 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
             'amqp.connected',
             'shared-db.connected',
             'identity-service.connected',
-            'identity-service.available',  # enables SSL support
             'config.changed',
-            'update-status']
+            'update-status',
+            'certificates.available']
         hook_set = {
             'when': {
                 'render_stuff': ('shared-db.available',